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Jim,
When I said "Don't you?", I meant the group. Not you
specifically.
I know you know better. :-)
Mike
--- Jim Sower <canarder@frontiernet.net> wrote:
> <...All charging systems should have protection for
> this. Don't you? ...>
> Yes. I've described it in some detail, about three
> times so far, on
> this thread. Now, the scenario of a "... load dump
> where the battery is
> disconnected ..." (and presumably all of the
> aircraft systems (can't see
> 100V with any load AT ALL - if then)) happening
> simultaneously with
> regulator failure to full output ... would be ...
> ???
>
> PVORT for three days now :o) ... Jim S.
>
>
> Michael LaFleur wrote:
>
> >In the case of a load dump, where the battery is
> >disconnected for a charging circuit, you will see
> more
> >than 100 volts.
> >
> >The alternator, being low impedance will cause
> large
> >positive transients. Simultabeously, the collapsing
> >field will cause negative field decay transients.
> >These can and will be in excess of 100 volts. All
> >charging systems should have protection for this.
> >Don't you?
> >
> >--- Jim Sower <canarder@frontiernet.net> wrote:
> >
> >
> >
> >>Finn Lassen wrote:
> >>
> >>
> >>
> >>>I think the +100 volts statement relates to no
> >>>
> >>>
> >>battery load. Have you
> >>
> >>
> >>>/anyone actually /seen/ that happen? I guess if
> >>>
> >>>
> >>the electrical system
> >>
> >>
> >>>was designed so that a contactor could disconnect
> >>>
> >>>
> >>the battery from the
> >>
> >>
> >>>load circuits and the load circuits (avionics)
> >>>
> >>>
> >>still be connected to
> >>
> >>
> >>>the alternator you would have a situation where
> >>>
> >>>
> >>you could wave your
> >>
> >>
> >>>avionics goodbye.
> >>>Perhaps. But that wouldn't be very clever.
> >>>
> >>>
> >>Anyone who designed his
> >>
> >>
> >>>system to protect his avionics from a Battery
> over
> >>>
> >>>
> >>voltage and ignored
> >>
> >>
> >>>the Alternator deserves whatever happens.
> >>>Let's say on top of that that one (or all) of the
> >>>
> >>>
> >>three retifiers
> >>
> >>
> >>>shorted out too, you'd have 100 volts A/C into
> >>>
> >>>
> >>your avionics. Not a
> >>
> >>
> >>>pretty picture. (I've seen Zener diodes short out
> >>>
> >>>
> >>regularily due to
> >>
> >>
> >>>overload/voltage; rectifier diodes usually fail
> >>>
> >>>
> >>open - but not
> >>
> >>
> >>>always). We're stretching a bit here aren't we?
>
> >>>
> >>>
> >>Back to the 100 V
> >>
> >>
> >>>that we've already agreed can't happen, shorted
> >>>
> >>>
> >>diodes causing AC
> >>
> >>
> >>>(which I'm not at all sure can happen), all three
> >>>
> >>>
> >>rectifiers (that's
> >>
> >>
> >>>all SIX diodes shorting at the same time (none of
> >>>
> >>>
> >>them failing open
> >>
> >>
> >>>which is more common), zener failing, etc. If a
> >>>
> >>>
> >>diode fails every
> >>
> >>
> >>>1000 hrs, the whole bank failing would happen
> >>>
> >>>
> >>every 1000^6 hours.
> >>
> >>
> >>>That's a one with TWENTY ONE zeros behind it.
> >>>
> >>>
> >>I think I can live with that ... Jim S.
> >>
> >>
> >>
> >>>Finn
> >>>
> >>>Jim Sower wrote:
> >>>
> >>>
> >>>
> >>>><... the alternator is capable of producing over
> >>>>
> >>>>
> >>100 volts ...>
> >>
> >>
> >>>>I don't think so ...
> >>>>...
> >>>>Bottom line, with the regulator failed (or
> >>>>
> >>>>
> >>bypassed) to send full B+
> >>
> >>
> >>>>voltage to the field, the charging voltage never
> >>>>
> >>>>
> >>exceed 18V in my
> >>
> >>
> >>>>experience.
> >>>>
> >>>>
> >>>
> >>>
> >>>--
> >>>Homepage: http://www.flyrotary.com/
> >>>Archive and UnSub:
> >>>
> >>>
> >>http://mail.lancaironline.net/lists/flyrotary/
> >>
> >>
> >>>
> >>>
> >
> >
> >--
> >Homepage: http://www.flyrotary.com/
> >Archive and UnSub:
> http://mail.lancaironline.net/lists/flyrotary/
> >
> >
>
=== message truncated ===
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